Conventional crystal silicon photovoltaic cell modules are configured as follows.
That is, as a protection glass (also called cover glass) of a module surface, a tempered glass is used in consideration of resistance to shock. On one side of the tempered glass there is an asperity pattern formed by embossment to facilitate adhesion of the glass to a sealing material (which is usually a resin containing an ethylene vinyl acetate copolymer as a main component and also called filler).
In addition, the asperity pattern is formed inside, and the surface of the photovoltaic cell module is smooth. Furthermore, under the protection glass are provided a sealing material for protecting and sealing photovoltaic cell elements and tab lines, and a back film.
In JP-A-2000-328053 and the like, there have been proposed many methods in which the wavelength of light of UV region or infrared region in sunlight spectrum, which does not contribute to electricity generation, is converted using a fluorescent substance (also called light emission material) to provide a layer that emits light of a wavelength region capable of contributing to electricity generation on a light receiving side of photovoltaic cells.
In addition, JP-A No. 2006-303033 proposes a photovoltaic cell module including, between its front cover and its crystalline silicon element, a sealing material which includes a rare earth complex as a fluorescent substance.
Furthermore, conventionally, for example, as disclosed in JP-A No. 2006-303033 and JP-A No. 2003-51605, as a transparent sealing material for photovoltaic cells, there has been widely used an ethylene-vinyl acetate copolymer to which thermosetting properties have been provided.